We propose a controlled, prosective study of the effects of plasmapheresis on the short-term and long-term courses of patients with severe forms of lupus glomerulonephritis. This is one of two applications being submitted for this clinical trial. This application proposes support for the Clinical Coordinating Center of the Lupus Nephritis Collaborative Study Group. A separate application proposes support of the Biostatistical Coordinating Center (John M. Lachin, D.Sc., Principal Investigator). The trial will involve approximately 12 collaborating clinics. A population of 200 patients will be followed for periods up to 5 years. The primary end point is mortality or renal failure. The clinical management protocols are designed to attain the following purposes: (1) To determine whether plasmapheresis has a beneficial effect in this population - a group of patients with severe lupus glomerulonephritis defined in precise histologic terms will be randomly assigned to therapy with (a) prednisone plus cyclophosphamide, or (b) plasmapheresis plus prednisone/ cyclophosphamide. These patients will be assigned to this primary protocol at entry and when they fulfill the definition of a severe recurrent manifestation of lupus glomerulonephritis. (2) The second purpose of the protocols is to provide a mechanism for standardized definition and management of intercurrent complications of the disease process or its management. Lupus being a complicated disease, these protocols attempt to take into account intercurrent events in order to provide some uniformity to the overall management of the patients during the period of time they are being studied. The goal of this study is to determine whether plasmapheresis contributes to improvement of the prognosis of a population of lupus patients with serious glomerular disease. In addition to the primary end points of mortality and renal failure, other variables will be studied, including rate of loss of renal function, rate of appearance of intercurrent renal and nonrenal exacerbations, the amount of prednisone administered during the period of study and the incidence of complications.